Day3

day3/rucksack.c

@@ -0,0 +1,93 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define BUFFER_SIZE 64
+#define GROUP_SIZE   3
+ 
+#define score(ch) (ch < 'a' ? ch - 'A' + 27 : ch - 'a' + 1)
+
+char firstMatch(char*, char*, int);
+void cp(char*, char*);
+char badge(char**, char*);
+
+int main() {
+    char buf[BUFFER_SIZE], *p, *q, c;
+    char *prev[GROUP_SIZE - 1];
+    for (int i = 0; i < GROUP_SIZE - 1; i++) {
+        prev[i] = (char*)malloc(BUFFER_SIZE);
+    }
+    int l = 0, sum = 0, sum2 = 0, gruppen = 0;
+    p = buf;
+    while ((c = getchar()) != EOF) {
+        *p++ = c;
+        l++;
+        if (c == '\n') {
+            p = buf;
+            q = p + l/2;
+
+            c = firstMatch(p, q, l/2);
+            sum += score(c);
+
+            if (gruppen != GROUP_SIZE - 1) {
+                cp(p, prev[gruppen]);
+            } else {
+                c = badge(prev, p);
+                sum2 += score(c);
+            }
+
+            gruppen == GROUP_SIZE - 1 ? gruppen = 0 : gruppen++;
+
+            memset(buf, 0, BUFFER_SIZE);
+            p = buf;
+            l = 0;
+        }
+    }
+
+    for (int i = 0; i < GROUP_SIZE - 1; i++) {
+        free(prev[i]);
+    }
+
+    printf("%i\n", sum);
+    printf("%i\n", sum2);
+}
+
+char firstMatch(char *p, char *q, int l) {
+    for (int i = 0; i < l; i++) {
+        for (int j = 0; j < l; j++) {
+            if (p[i] == q[j]) return p[i];
+        }
+    }
+    return -1;
+}
+
+void cp(char* p, char* q) {
+    while((*q++ = *p++) != '\n') {}
+}
+
+char badge(char** prev, char* p) {
+    // This could be done more efficiently
+    int match;
+    char *q;
+    p--;
+    while(*(++p) != '\n') {
+        for (int i = 0; i < GROUP_SIZE - 1; i++) {
+            // Iterate every string to find a match
+            match = 0;
+            q = prev[i] - 1;
+            while(*(++q) != '\n') {
+                if (*q == *p) {
+                    match = 1;
+                    break;
+                }
+            }
+            if (!match) {
+                break;
+            }
+        }
+        if (match) {
+            return *p;
+        }
+    }
+    return -1;
+}